There's just one thing to tip you off that this is a film by David Cronenberg. The gunshot wounds. In an otherwise straight-looking, straight-talking movie, they stand out like lush and evil-smelling exotic flowers. Now obviously, getting shot in the face can't look pretty. But surely to God it doesn't look like this. The ghastly contusions and lesions where the bullet goes in gibber like some extra rubbery mandible, or like the face of the Alien as it emerges from John Hurt's stomach. These cannot appear in any medical textbook known to man. It is as if the wounded person has been suddenly whisked at warp-speed to Planet Cronenberg to have the injury seeded with a kinky bacterium and then transported back to Earth for the resulting metastasis to be filmed.

Otherwise it's all quite normal. Sort of. Cronenberg has here directed an adaptation of a graphic novel by John Wagner and Vince Locke - part of a publishing series which includes The Road to Perdition, recently shot by Sam Mendes - although this has a cleaner, more uncluttered design, is more relaxed and less obviously concerned to transmit the super-cool novelty of its comic-book origins. It is a rather gripping and stylish film, a kind of black serio-comedy. A little middle-of-the-road for Cronenberg, maybe, but for him this has turned out to be the fast lane.

A History of Violence is about the intrusion of violent and bizarre outsiders in a peaceful all-American small town whose inhabitants' lives are drawn with surprising wit and sympathy. It looks like Frank Capra, and Main Street resembles the one in Phoenix, Arizona, where the real estate office is to be found in Psycho. Viggo Mortensen plays Tom: a rugged, regular guy whose handsome features are always on the point of being shyly drawn upwards into a "Shucks". He runs a modest little diner, working behind the counter in an apron, serving coffee and slices of generic pie, exchanging badinage with his employees: a place where people say "See you in church!" without getting a laugh. Tom has a bright, nervy son, Jack (Ashton Holmes) who is being pushed around by a jock bully in school, a sweet pre-teen daughter and a wife, Edie (Maria Bello) who, after 15 years of marriage, still loves and desires him - enough to dress up as a fantasy cheerleader for some raunchy intra-marital soixante-neuf. One of the interesting achievements of this film is to argue for the intensity, even violence, possible in married love.

Everyone's lives change when some itinerant bad guys roll into town and make the serious mistake of trying to stick up the local diner - and indeed mess with the womenfolk. Quiet Tom re-enacts the final verse of The Coward of the County, and to his embarrassment finds himself feted by the national media as an American smalltown hero: the man who disarmed two criminals and showed them some rough justice. Tom finds that his celebrity has attracted the attention of some very scary individuals. A big-city wiseguy played by Ed Harris - sporting a spectacularly yucky Cronenberg-wound on his face - shows up, and Tom's moment of heroism unlocks some secrets in his past and draws him and his family into a terrifying world of violence.

Cronenberg is not known for subtlety exactly, and this is hardly a subtle film, but there is something intriguing and understated in the way he contrives a syncopation of narrative and character. It looks on paper like a regular father-son drama, or a standard-issue gangster film, but there's a Twilight Zoney offness and weirdness. The explicit alienness of films like Crash or Dead Ringers or eXistenZ has been coiled and hidden in the movie's fabric. He gets an unreality effect, a note of superhero or secret-identity fantasy, that works particularly well when Tom's teenage boy suddenly finds in himself the capacity for aggression necessary to stand up to his tormentors at school. On the strength of this, Cronenberg might well find himself offered the next Spider-Man movie.

The director saves his best flourish for his final act: a terrifically funny performance from William Hurt as the glowering gangster who finally confronts Tom. He is living a life of preposterous self-importance in the pseudo-baronial stately home that he considers commensurate with a vicious killer of his standing. Hurt's habitual puzzled, quizzical, faintly nettled look - a regular feature of his performances since the days of Broadcast News - has at last come into its own as a kind of murderous grumpiness. His presence provides the movie with an uproarious finale - which, however, might not be enough to satisfy some people, inside and outside the director's fanbase, who will complain Cronenberg has allowed himself to be washed into the commercial mainstream. This isn't true. He has dammed and diverted the mainstream and made it work for him.